Drinking a small amount of olive oil in the morning is not harmful for most people and can offer a few real, evidence-backed benefits, particularly for digestion, blood sugar management, and cholesterol. The practice has roots in Mediterranean folk tradition and has gained traction on social media, but the science is more specific than the hype suggests. The timing matters less than you might think, the type of olive oil matters more than most people realize, and the dose range that helps is narrower than influencers often recommend.
What Happens When Olive Oil Hits an Empty Stomach
When you swallow a tablespoon of olive oil first thing in the morning, your body treats it the way it treats any incoming fat: the stomach slows down, the gallbladder contracts to release bile, and the gut begins secreting hormones that manage digestion and appetite. Olive oil is roughly 73 percent oleic acid, a monounsaturated fat that is particularly effective at triggering this hormonal cascade. In a study comparing olive oil and pure oleic acid, both slowed gastric emptying and prompted the release of gut hormones like cholecystokinin (CCK) and peptide YY, both of which signal fullness to the brain.1e-SPEN Journal. Effects of oleic acid and olive oil on gastric emptying, gut hormone secretion and appetite in lean and overweight or obese males
Oleic acid-rich fats like olive oil also stimulate stronger gallbladder emptying than some other fat types. Research comparing trioleate (a triglyceride of oleic acid, the dominant fat in olive oil) to fish oil found that trioleate produced significantly greater gallbladder contraction and a much larger release of CCK.2PubMed. Gallbladder emptying and cholecystokinin response to fish oil and trioleate ingestion This is worth knowing if you have sluggish bile flow: olive oil on an empty stomach is a potent natural trigger for bile release. For people who have had their gallbladder removed, however, that same potency can backfire and cause cramping or loose stools.
The Blood Sugar Case for Morning Olive Oil
One of the stronger arguments for drinking olive oil before or with a morning meal is its effect on blood sugar. When healthy volunteers ate a meal prepared with extra virgin olive oil (EVOO) versus the same meal without it, those who got the EVOO saw significantly lower blood glucose two hours after eating, along with improved insulin secretion and higher levels of GLP-1, a hormone that helps regulate blood sugar.3Nutrition & Diabetes. Extra virgin olive oil use is associated with improved post-prandial blood glucose and LDL cholesterol in healthy subjects The same study compared EVOO to corn oil and found that EVOO produced a smaller glucose spike and a better insulin response.
Animal research adds further context. Mice fed a high-fat diet supplemented with EVOO showed improved insulin sensitivity, better glucose tolerance, and healthier insulin-producing cells compared to mice on the same high-fat diet without EVOO.4PubMed Central. Extra virgin olive oil diet intervention improves insulin resistance and islet performance in diet-induced diabetes in mice These are mouse findings and you should not extrapolate dose-for-dose to humans, but they line up with what the human trials show: olive oil, especially EVOO, helps moderate the blood sugar rollercoaster after a meal.
There is also a circadian angle to consider. Research on the body’s internal clock and metabolism suggests that several metabolic rhythms, including those governing glucose processing and lipid handling, peak in the biological morning or around midday.5PubMed Central. Circadian regulation of glucose, lipid, and energy metabolism in humans This does not prove that olive oil is better in the morning than at dinner, but it does suggest your body is primed to handle fat and glucose more efficiently earlier in the day. If you are going to consume olive oil for metabolic benefits, morning is at least a reasonable time to do it.
Constipation Relief
This is the benefit with the most direct and consistent clinical support. If you are dealing with chronic constipation, olive oil on an empty stomach may genuinely help. A randomized trial gave constipated adults either extra virgin olive oil or refined olive oil daily for four weeks. Both groups improved, but the EVOO group improved dramatically more: their constipation symptom scores dropped from an average of about 11 to roughly 3.5, while the refined olive oil group went from about 11 to around 7.7.6PubMed Central. Comparative efficacy of extra virgin olive oil versus refined olive oil in the treatment of individuals suffering from constipation: A double-blind randomized clinical trial study
A separate trial in hemodialysis patients (a population with especially stubborn constipation) compared olive oil, flaxseed oil, and mineral oil. Olive oil performed as well as mineral oil, the standard medical laxative, across five out of six constipation symptoms, with significant improvement in frequency and stool consistency.7Journal of Renal Nutrition. The Short-Term Effects of Olive Oil and Flaxseed Oil for the Treatment of Constipation in Hemodialysis Patients Flaxseed oil, by comparison, only improved two of the six symptoms. The mechanism is straightforward: olive oil lubricates the intestinal lining, stimulates bile flow, and the oleic acid itself promotes intestinal motility.
Appetite and Fullness
Some people drink olive oil in the morning expecting it to crush their appetite for hours. The reality is more modest. Olive oil does trigger satiety hormones, as mentioned above, and animal research has found that EVOO increases stomach retention and reduces food intake more effectively than some other oils, including sunflower oil.8PubMed Central. Brain Perception of Different Oils on Appetite Regulation: An Anorectic Gene Expression Pattern in the Hypothalamus Dependent on the Vagus Nerve In that research, EVOO’s appetite-suppressing effect persisted even when autonomic nerve responses were blocked, suggesting it works through multiple pathways.
But here is the practical reality: a tablespoon of olive oil contains about 120 calories and 14 grams of fat. If you drink it and then eat a normal breakfast on top of it, you have added 120 calories to your morning without necessarily eating less at lunch. The satiety effect is real but mild. You are not going to skip meals because you had a shot of olive oil. If appetite control is your goal, you will get more mileage from pairing olive oil with fiber and protein at a meal than from drinking it neat.
Cholesterol and Heart Health
The relationship between olive oil and cardiovascular markers is well established but comes with an important nuance. A controlled trial found that olive oil rich in polyphenols reduced the number of total and small LDL particles by roughly 12 and 15 percent respectively, and decreased a key protein associated with LDL production by about 6 percent. The same trial showed that olive oil low in polyphenols actually raised those markers.9PubMed Central. Olive Oil Polyphenols Decrease LDL Concentrations and LDL Atherogenicity in Men in a Randomized Controlled Trial This is a crucial finding because it tells you that the cardiovascular benefit is tied specifically to the polyphenol content, which varies enormously between different olive oils.
The nuance gets more interesting when you look at what happens to your blood vessels right after a high-fat olive oil meal. One study found that endothelial function, the ability of blood vessels to dilate properly, was temporarily worse after a high-fat olive oil meal compared to a high-fat walnut meal.10PubMed. Acute effects of high-fat meals enriched with walnuts or olive oil on postprandial endothelial function This does not mean olive oil is bad for your heart. It means that a large bolus of any fat, including olive oil, produces a temporary dip in vascular function. The long-term trajectory is what matters for heart disease risk, and the long-term data on EVOO is strongly positive.
For context, when researchers compared a meal enriched with EVOO to one enriched with butter in people with type 1 diabetes, the EVOO meal significantly improved blood vessel dilation while the butter meal made it worse.11PubMed Central. Effect of Extra Virgin Olive Oil and Butter on Endothelial Function in Type 1 Diabetes The takeaway is that olive oil is meaningfully better than saturated fat for vascular health, even if it is not as impressive in a head-to-head with walnuts right after a meal.
Liver Protection
Fatty liver disease affects a large and growing share of the population, and olive oil consumption appears to work in its favor. Research has found that an olive oil-rich diet reduces fat accumulation in the liver and improves the postprandial response of triglycerides and glucose in people who are insulin-resistant.12PubMed Central. Olive oil consumption and non-alcoholic fatty liver disease A systematic review examining multiple studies found that olive oil groups consistently showed significant reductions in liver fat as measured by ultrasound, and some studies also reported improvements in liver enzymes, which are markers of liver inflammation.13Journal of Functional Foods. Effects of olive oil on hepatic steatosis and liver enzymes: A systematic review
None of these liver studies isolated morning consumption as a variable, so there is no specific evidence that drinking olive oil in the morning is better for your liver than using it at dinner. The benefit comes from regular intake over time rather than from a particular dosing schedule.
Extra Virgin vs. Refined Olive Oil
This is the single most important practical distinction that most articles on the topic skip over, and the evidence is unambiguous: extra virgin olive oil delivers substantially more benefit than refined olive oil for almost every outcome studied. The constipation trial described above found that EVOO was roughly twice as effective as refined olive oil at reducing symptoms. The cholesterol trial showed that high-polyphenol olive oil lowered LDL particles while low-polyphenol oil raised them. The difference comes down to polyphenols and other bioactive compounds that survive in EVOO but are stripped out during the refining process.
EVOO retains compounds like oleocanthal (which has anti-inflammatory properties similar to ibuprofen), hydroxytyrosol, and oleuropein. These polyphenols have documented effects on gut bacteria, acting as prebiotics that promote beneficial bacteria, increase production of short-chain fatty acids, and reduce populations of harmful bacteria.14PubMed Central. Dietary EVOO Polyphenols and Gut Microbiota Interaction: Are There Any Sex/Gender Influences? Refined olive oil still provides oleic acid and the basic mechanical benefits of fat (bile stimulation, lubrication), but the metabolic and anti-inflammatory extras largely disappear. If you are going to drink olive oil on purpose for health reasons, the cost difference between EVOO and refined is well worth paying.
Stomach and Gut Protection
One concern people often raise is whether drinking oil on an empty stomach could damage the stomach lining. The evidence points in the opposite direction. In animal research, EVOO actually protected the stomach lining from damage caused by H. pylori infection. Mice infected with H. pylori and then treated with EVOO showed fewer erosions, less damage to the stomach lining, and near-normal tissue appearance compared to untreated infected mice.15PubMed Central. Extra virgin olive oil inhibits Helicobacter pylori growth in vitro and the development of mice gastric mucosa lesions in vivo EVOO and its phenolic compounds also inhibited H. pylori growth in lab conditions, though this needs further human study before it can be recommended as a treatment.
The gut microbiome effects are broader than just stomach protection. As noted above, EVOO polyphenols function as a kind of prebiotic, selectively feeding beneficial gut bacteria. This is a two-way relationship: the gut bacteria also metabolize EVOO polyphenols into forms the body can absorb more easily, so a healthy gut microbiome may actually amplify the benefits of the olive oil you drink.
How Much to Drink and Who Should Be Careful
Most of the studies showing benefits used the equivalent of one to two tablespoons of olive oil per day, which works out to roughly 15 to 30 milliliters. That range gives you enough oleic acid and polyphenols to see measurable effects without adding an excessive caloric load. Going beyond two tablespoons adds calories quickly and can cause nausea, especially on an empty stomach. Some people experience a burning sensation in the throat from the oleocanthal in high-quality EVOO, which is actually a sign of good polyphenol content, but it can feel unpleasant first thing in the morning.
People who should approach morning olive oil with caution include:
- Those without a gallbladder: the strong bile-stimulating effect can cause cramping and diarrhea.
- People on blood thinners: olive oil has mild antiplatelet effects that could theoretically add to anticoagulant medication, though this has not been shown to be clinically dangerous at normal dietary doses.
- Anyone with a fat malabsorption disorder: conditions like chronic pancreatitis or bile duct obstruction can make it difficult to process a concentrated dose of fat.
- People watching their weight carefully: a tablespoon of olive oil every morning adds roughly 840 calories per week, enough to matter if you are in a caloric deficit.
For most healthy adults, one tablespoon of high-quality EVOO on an empty stomach will not cause problems and may offer the digestive and metabolic benefits supported by the research. If straight olive oil is unpleasant, squeezing some lemon juice into it or drizzling it over a few bites of bread achieves the same thing with less of a medicinal feeling.
The Oil Pulling Tangent
While researching olive oil and morning routines, you will inevitably run across claims about oil pulling, the practice of swishing oil around your mouth for 10 to 20 minutes. This is a completely different practice from drinking olive oil and has a separate evidence base rooted in traditional Ayurvedic medicine. Some small studies suggest oil pulling may help reduce harmful oral bacteria and improve gum health, but the evidence is modest and the mechanism is mechanical (trapping bacteria in the oil) rather than nutritional. Swishing olive oil and drinking olive oil are not interchangeable practices. If your goal is metabolic or digestive benefits, drinking is the relevant route. If your goal is oral hygiene, standard brushing and flossing remain far better supported.
What “Morning” Actually Adds
The honest answer to the “in the morning” part of the question is that the timing itself is a minor factor compared to the quality of the oil and the consistency of the habit. The circadian evidence suggests your body is somewhat better at processing fats and glucose earlier in the day, which is a modest point in morning consumption’s favor.5PubMed Central. Circadian regulation of glucose, lipid, and energy metabolism in humans The empty-stomach angle means the olive oil reaches your intestines faster without competing with other foods, which may slightly amplify the bile-stimulating and laxative effects. But none of the major clinical trials specifically tested morning versus evening dosing, so any claim that morning is dramatically superior is extrapolation rather than evidence.
What does matter is regularity. The constipation trials ran for four weeks of daily use. The cholesterol trial required sustained consumption over weeks. The liver benefits appeared in studies of habitual olive oil use. A single morning shot of olive oil will not transform your health. A daily tablespoon of good EVOO, whether in the morning or split between meals, adds up over months into the kind of pattern the Mediterranean diet research has consistently linked to lower cardiovascular risk, better metabolic markers, and reduced inflammation.